In the field of data communications, communications networks typically utilize techniques designed to maintain or improve the integrity of signals being transmitted via the network (“transmission signals”). To protect signal integrity, the communications networks should, at a minimum, satisfy compliance standards that are established by standards committees, such as the Institute of Electrical and Electronics Engineers (IEEE). The compliance standards help network designers provide communications networks that achieve at least minimum levels of signal integrity as well as some standard of compatibility.
One prevalent type of communication system uses twisted pairs of wires to transmit signals. In twisted pair systems, information such as video, audio and data are transmitted in the form of balanced signals over a pair of wires. The transmitted signal is defined by the voltage difference between the wires.
Crosstalk can negatively affect signal integrity in twisted pair systems. Crosstalk is unbalanced noise caused by capacitive and/or inductive coupling between wires and a twisted pair system. Communications networks include areas that are especially susceptible to crosstalk because of the proximity of the transmission signals. In particular, communications networks include connectors that bring transmission signals in close proximity to one another. For example, the contacts of traditional connectors (e.g., jacks and plugs) used to provide interconnections in twisted pair telecommunications systems are particularly susceptible to crosstalk interference.
Existing jacks and plugs include crosstalk compensating arrangements that are designed to reduce crosstalk for a range of frequencies intended to be used by the jack for data communications. Such crosstalk compensating arrangements are typically useable across a known range of frequencies to reduce crosstalk to levels that are acceptable according to known standards. For example, Category 5-compatible jack and plug arrangements are intended to be operable at about 100 MHz, and supports up to 1000BASE-T communication rates. In contrast, Category 6a-compatible cable supports up to about 500 MHz signal frequencies, and 10 Gigabit (10 GBASE-T) data communication rates. Existing circuits useable to compensate for crosstalk in these circuits are operable across this entire range of frequencies.
As data rates continue to increase, still higher frequencies are required for communication, leading to signal frequencies needed that are in excess of 500 MHz, and up to about 1000 MHz. However, existing crosstalk compensation arrangements do not provide sufficient crosstalk compensation at these increased frequencies. Although some circuits exist that are intended to provide crosstalk compensation at these higher frequencies, those circuits have drawbacks. For example, because one goal of such a communication network is backward-compatibility, it is desired for the same jack to be useable in connection with higher frequency signals, while maintaining acceptable crosstalk levels for lower, preexisting frequencies.
Some existing attempts to address this issue involve use of differently formatted plugs and jacks for higher frequency signals. Such jacks include a jack compatible with the IEC 60603-7-7 interface standard, which in contrast to existing RJ-45 jacks, separates the middle two pairs of a four-pair connector and places a differential pair at each of four corners of a plug-jack combination. This physical separation of pairs reduces crosstalk among the pairs for higher frequency applications. In other solutions, a physical switch can be incorporated into a jack and that is actuated by a special-purpose plug. The physical switch can activate a higher-frequency compensation circuit, whereas in the absence of its actuation, existing crosstalk compensation frequencies are provided. However, even these arrangements have limitations in terms of the types of circuits useable, and are susceptible to switch failure.
For these and other reasons, improvements are desirable.